The present invention relates to a method for verifying the correct operation of a safety valve of an oil well.
In accordance with safety standards, a production well head must be fitted with a safety valve disposed in the well approximately 30 meters below the surface of the ground or of the sea bottom. This valve, most of the time hydraulically actuated, is intended to close the well in the case of a serious accident, for example in the case of a blow out.
In general, such a valve is designed to have a closed rest position, the valve being held in an open position under the effect of the hydraulic pressure sent from the surface by a hydraulic line situated along the production string. If required, the hydraulic pressure is stopped, which then leads to closure of the valve. Thus, any incident or destruction at the well head leads in this manner to the automatic closure of the safety valve.
Since such a valve constitutes an essential element for well security, it is necessary to monitor periodically the correct operation of the valve and of the hydraulic control system. However, actuating the valve is not sufficient in the present case because it is not possible to detect with certainty a possible malfunction such as partial opening which could lead, after a period of production, to the valve being rendered inoperative.